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Eliminate double counting of treatment subrelease stats in HugePageFiller. #704

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Eliminate double counting of treatment subrelease stats in HugePageFiller. #704

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2 changes: 0 additions & 2 deletions tcmalloc/huge_page_filler.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1919,7 +1919,6 @@ inline Length HugePageFiller<TrackerType>::HandleReleaseFree(
PageTracker* tracker) {
RemoveFromFillerList(tracker);
Length released_length = tracker->ReleaseFree(unback_);
subrelease_stats_.total_pages_subreleased += released_length;
unmapped_ += released_length;
unmapping_unaccounted_ += released_length;
AddToFillerList(tracker);
Expand All @@ -1939,7 +1938,6 @@ inline Length HugePageFiller<TrackerType>::HandleUnbackedHugePage(
PageTracker* tracker, const PageBitmap& unbacked) {
RemoveFromFillerList(tracker);
Length unmapped_length = tracker->MarkSubreleased(unbacked);
subrelease_stats_.total_pages_subreleased += unmapped_length;
unmapped_ += unmapped_length;
unmapping_unaccounted_ += unmapped_length;
AddToFillerList(tracker);
Expand Down
91 changes: 82 additions & 9 deletions tcmalloc/huge_page_filler_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -842,7 +842,7 @@ TEST_F(FillerTest, ReleaseFreePagesWhenAnyPageIsSwappedRespectsClock) {
TreatHugepageTrackers(EnableCollapse::kDisabled,
EnableUnfilteredCollapse::kDisabled,
ReleaseStalePages::kDisabled, &pageflags, &residency);
EXPECT_EQ(filler_.subrelease_stats().total_pages_subreleased, Length(1));
EXPECT_EQ(ReleasePages(Length(0)), Length(1));
EXPECT_EQ(GetHugePageTreatmentStats().treated_pages_subreleased, 1);
DeleteVector(p1);
}
Expand Down Expand Up @@ -989,7 +989,7 @@ TEST_F(FillerTest, ReleaseFreePagesWhenAnyPageIsSwapped) {
ReleaseStalePages::kDisabled, &pageflags, &residency);
// We expect to release the two free pages, since the second native page is
// swapped. We expect to log this correctly.
EXPECT_EQ(filler_.subrelease_stats().total_pages_subreleased, Length(2));
EXPECT_EQ(ReleasePages(Length(0)), Length(2));
EXPECT_EQ(GetHugePageTreatmentStats().treated_pages_subreleased, 2);
std::string buffer = PrintToString(1024 * 1024, [&](Printer& printer) {
PageHeapSpinLockHolder l;
Expand All @@ -1004,12 +1004,49 @@ TEST_F(FillerTest, ReleaseFreePagesWhenAnyPageIsSwapped) {
TreatHugepageTrackers(EnableCollapse::kDisabled,
EnableUnfilteredCollapse::kDisabled,
ReleaseStalePages::kDisabled, &pageflags, &residency);
EXPECT_EQ(filler_.subrelease_stats().total_pages_subreleased, Length(2));
EXPECT_EQ(ReleasePages(Length(0)), Length(0));
EXPECT_EQ(GetHugePageTreatmentStats().treated_pages_subreleased, 0);

DeleteVector(p1);
}

// Checks that pages released due to swapped page treatment are not double
// counted in subrelease_stats.
TEST_F(FillerTest, SubreleaseStatsNoDoubleCountSwapped) {
const Length kAlloc = kPagesPerHugePage;
std::vector<PAlloc> p1 = AllocateVector(kAlloc - Length(2));
ASSERT_TRUE(!p1.empty());

FakePageFlags pageflags;
FakeResidency residency;
for (const auto& pa : p1) {
pageflags.MarkHugePageBacked(pa.p.start_addr(),
/*is_hugepage_backed=*/false);

Bitmap<kMaxResidencyBits> unbacked, swapped;
swapped.SetRange(/*index=*/1, /*n=*/1);
residency.SetUnbackedAndSwappedBitmaps(pa.p.start_addr(), unbacked,
swapped);
pageflags.SetStaleBitmap(pa.p.start_addr(), {});
}

ASSERT_EQ(filler_.size(), NHugePages(1));
TreatHugepageTrackers(EnableCollapse::kDisabled,
EnableUnfilteredCollapse::kDisabled,
ReleaseStalePages::kDisabled, &pageflags, &residency);

EXPECT_EQ(ReleasePages(Length(0)), Length(2));
EXPECT_EQ(filler_.subrelease_stats().num_pages_subreleased, Length(2));
EXPECT_EQ(filler_.subrelease_stats().total_pages_subreleased, Length(0));

PAlloc extra = Allocate(Length(1));
EXPECT_EQ(filler_.subrelease_stats().num_pages_subreleased, Length(0));
EXPECT_EQ(filler_.subrelease_stats().total_pages_subreleased, Length(2));

Delete(extra);
DeleteVector(p1);
}

// Checks that we don't release pages when there aren't any pages that are
// swapped.
TEST_F(FillerTest, ReleaseNoFreePages) {
Expand Down Expand Up @@ -1089,7 +1126,7 @@ TEST_F(FillerTest, CheckAllocationsComeFromIntactHugepage) {
ReleaseStalePages::kDisabled, &pageflags, &residency);

// There should be two pages released, from p1's hugepage.
EXPECT_EQ(filler_.subrelease_stats().total_pages_subreleased, Length(2));
EXPECT_EQ(ReleasePages(Length(0)), Length(2));
EXPECT_EQ(GetHugePageTreatmentStats().treated_pages_subreleased, 2);
// We make an allocation. We expect it to come from the same hugepage as
// the elements of p3, since this hugepage has not been subreleased from,
Expand Down Expand Up @@ -1916,7 +1953,7 @@ TEST_F(FillerTestWithSubreleaseUnbacked, SubreleaseUnbackedPages) {
TreatHugepageTrackers(EnableCollapse::kDisabled,
EnableUnfilteredCollapse::kDisabled,
ReleaseStalePages::kDisabled, &pageflags, &residency);
EXPECT_EQ(filler_.subrelease_stats().total_pages_subreleased, Length(1));
EXPECT_EQ(ReleasePages(Length(0)), Length(1));
EXPECT_EQ(GetHugePageTreatmentStats().treated_pages_unbacked_subreleased, 1);
std::string buffer = PrintToString(1024 * 1024, [&](Printer& printer) {
PageHeapSpinLockHolder l;
Expand All @@ -1928,6 +1965,42 @@ TEST_F(FillerTestWithSubreleaseUnbacked, SubreleaseUnbackedPages) {
DeleteVector(p1);
}

// Checks that pages released due to unbacked page treatment are not double
// counted in subrelease_stats.
TEST_F(FillerTestWithSubreleaseUnbacked, SubreleaseStatsNoDoubleCountUnbacked) {
randomize_density_ = false;
const Length kAlloc = kPagesPerHugePage - Length(1);
std::vector<PAlloc> p1 = AllocateVector(kAlloc);
ASSERT_TRUE(!p1.empty());

FakePageFlags pageflags;
FakeResidency residency;
for (const auto& pa : p1) {
pageflags.MarkHugePageBacked(pa.p.start_addr(),
/*is_hugepage_backed=*/false);
Bitmap<kMaxResidencyBits> unbacked, swapped;
unbacked.SetRange(0, kMaxResidencyBits);
residency.SetUnbackedAndSwappedBitmaps(pa.p.start_addr(), unbacked,
swapped);
pageflags.SetStaleBitmap(pa.p.start_addr(), {});
}

TreatHugepageTrackers(EnableCollapse::kDisabled,
EnableUnfilteredCollapse::kDisabled,
ReleaseStalePages::kDisabled, &pageflags, &residency);

EXPECT_EQ(ReleasePages(Length(0)), Length(1));
EXPECT_EQ(filler_.subrelease_stats().num_pages_subreleased, Length(1));
EXPECT_EQ(filler_.subrelease_stats().total_pages_subreleased, Length(0));

PAlloc extra = Allocate(Length(1));
EXPECT_EQ(filler_.subrelease_stats().num_pages_subreleased, Length(0));
EXPECT_EQ(filler_.subrelease_stats().total_pages_subreleased, Length(1));

Delete(extra);
DeleteVector(p1);
}

// This test confirms that when enable_subrelease_unbacked is set to false,
// no unbacked pages are subreleased from non-hugepage-backed trackers.
TEST_F(FillerTest, SubreleaseUnbackedPagesDisabled) {
Expand Down Expand Up @@ -2099,7 +2172,7 @@ TEST_F(FillerTestWithSubreleaseUnbacked, SubreleaseUnbackedAndSwapped) {
TreatHugepageTrackers(EnableCollapse::kDisabled,
EnableUnfilteredCollapse::kDisabled,
ReleaseStalePages::kDisabled, &pageflags, &residency);
EXPECT_EQ(filler_.subrelease_stats().total_pages_subreleased, Length(2));
EXPECT_EQ(ReleasePages(Length(0)), Length(2));
DeleteVector(p1);
}

Expand Down Expand Up @@ -2128,7 +2201,7 @@ TEST_F(FillerTestWithSubreleaseUnbacked, SubreleaseUnbackedRecovery) {
EnableUnfilteredCollapse::kDisabled,
ReleaseStalePages::kDisabled, &pageflags, &residency);

EXPECT_EQ(filler_.subrelease_stats().total_pages_subreleased, Length(10));
EXPECT_EQ(ReleasePages(Length(0)), Length(10));

std::vector<PAlloc> p2 = AllocateVector(Length(10));
ASSERT_TRUE(!p2.empty());
Expand Down Expand Up @@ -2190,7 +2263,7 @@ TEST_F(FillerTestWithSubreleaseUnbacked, SubreleaseUnbackedDonated) {
TreatHugepageTrackers(EnableCollapse::kDisabled,
EnableUnfilteredCollapse::kDisabled,
ReleaseStalePages::kDisabled, &pageflags, &residency);
EXPECT_EQ(filler_.subrelease_stats().total_pages_subreleased, Length(1));
EXPECT_EQ(ReleasePages(Length(0)), Length(1));
EXPECT_EQ(GetHugePageTreatmentStats().treated_pages_unbacked_subreleased, 1);
DeleteVector(p1);
}
Expand Down Expand Up @@ -2751,7 +2824,7 @@ TEST_F(FillerTestWithSubreleaseUnbacked, GardenReleasedTrackers) {
// well. We had 241 released pages. Now we should have 241 + 5 = 246 released
// pages.
EXPECT_EQ(pa.pt->released_pages(), N - Length(10));
EXPECT_EQ(filler_.subrelease_stats().total_pages_subreleased, N - Length(5));
EXPECT_EQ(ReleasePages(Length(0)), Length(5));
EXPECT_EQ(GetHugePageTreatmentStats().treated_pages_unbacked_subreleased, 5);

// Clean up.
Expand Down
17 changes: 3 additions & 14 deletions tcmalloc/span.h
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Expand Up @@ -254,10 +254,6 @@ class ABSL_CACHELINE_ALIGNED Span final : public SpanList::Elem {
[[nodiscard]] ObjIdx BitmapPtrToIdx(void* ptr, size_t size,
uint32_t reciprocal) const;
[[nodiscard]] void* BitmapIdxToPtr(ObjIdx idx, size_t size) const;
#ifndef TCMALLOC_INTERNAL_LEGACY_LOCKING
[[nodiscard]] void* BitmapIdxToPtr(ObjIdx idx, size_t size,
uintptr_t start) const;
#endif

#ifdef TCMALLOC_INTERNAL_LEGACY_LOCKING
static constexpr size_t kNonemptyIndexBits = 5;
Expand Down Expand Up @@ -610,15 +606,9 @@ inline Span::ObjIdx Span::OffsetToIdx(uintptr_t offset, uint32_t reciprocal) {
}

#ifndef TCMALLOC_INTERNAL_LEGACY_LOCKING
inline void* Span::BitmapIdxToPtr(ObjIdx idx, size_t size,
uintptr_t start) const {
TC_ASSERT_EQ(start, first_page().start_uintptr());
uintptr_t off = start + idx * size;
return reinterpret_cast<void*>(off);
}

inline void* Span::BitmapIdxToPtr(ObjIdx idx, size_t size) const {
return BitmapIdxToPtr(idx, size, first_page().start_uintptr());
uintptr_t off = first_page().start_uintptr() + idx * size;
return reinterpret_cast<void*>(off);
}
#endif

Expand Down Expand Up @@ -780,10 +770,9 @@ inline size_t Span::BitmapPopBatch(absl::Span<void*> batch,
return count;
#else
void** ptrs = batch.data();
const uintptr_t span_start = first_page().start_uintptr();
size_t popped = bitmap_.PopBatch(
[&](size_t offset) {
*ptrs++ = BitmapIdxToPtr(static_cast<ObjIdx>(offset), size, span_start);
*ptrs++ = BitmapIdxToPtr(static_cast<ObjIdx>(offset), size);
},
batch.size());
allocated_.store(allocated_.load(std::memory_order_relaxed) + popped,
Expand Down
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